The proposed research is aimed at developing protein microarrays as a superior technology oriented and viable product for the proteomics market. During Phase-I research, the PI and coworkers have successfully demonstrated the feasibility of fabricating protein microarrays with high selectivity and specificity, with uniform and controllable orientation of immobilized protein molecules, and with proteins in native states and easily accessible by targets in the solution. More importantly, preliminary research established not only the advantage of this chemistry in terms of selective protein immobilization without the need of pre-purification but also the necessity of orientational control in ensuring activity of the native state. The latter was demonstrated by the observation that enzymatic activity of oriented sulfotransferases on the surface was the same as that of solution phase enzymes, while randomly oriented enzymes on the surface showed less than 20% of the activity. Under Phase II funding, we propose (1) to establish the generality of oriented proteins on the surface in maintaining native activity; (2) to develop methods for on-chip refolding of immobilized proteins; (3) to further develop surface coating technology for commercialization. The success of Phase-II research will lead to the launch of a superior surface coating technology for protein microarrays with higher performance at potentially lower cost than current technology in the protein microarray market, which is very important for future large scale drug screening and disease diagnosis.